Around 2.8m cancers worldwide could be prevented if people adopted healthier lifestyles and better diets, a report says.

The huge toll of preventable cancers comes from an study published on Wednesday by the World Cancer Research Fund (WCRF), which comes 10 days before a United Nations summit in New York that will discuss ways to tackle the soaring rates of the disease around the world.

About 12m cancers are newly diagnosed each year, many of which will have some genetic or other trigger. But increasingly sedentary lifestyles, junk food, smoking and alcohol are key factors in around a quarter of them.

Experts hope the UN will take a lead by setting targets for cutting deaths from the lifestyle diseases – known as non-communicable diseases or NCDs – which include cancer, heart disease, diabetes and stroke. Campaigners hope issues such as junk food marketing to children on television, the high salt content of food, tobacco advertising in the developing world and alcohol prices will be addressed.

"Cancer and other lifestyle-related diseases are one of the biggest challenges we face today, and the UN summit later this month is a real turning point," said Professor Martin Wiseman, medical and scientific adviser to the WCRF.

"With millions of lives at risk around the world, the stakes are incredibly high. And while this is an issue facing millions globally, every day in the UK people are being diagnosed with a cancer that could have been prevented. People are still unaware that risk factors such as alcohol and obesity affect cancer risk while at the same time, from television advertising to the pricing of food, our society works in a way that discourages people from adopting healthy habits. But this summit offers the chance to look at public health issues at the international level."

Cutting cancer risk

1 Keep to a normal weight. Being overweight is a risk factor in breast and other cancers.